GHz bursts in MHz burst(BiBurst) enabling high-speed femtosecond laser ablation of silicon due to prevention of air ionization

作     者：Kotaro Obata Francesc Caballero-Lucas Shota Kawabata Godai Miyaji Koji Sugioka Kotaro Obata;Francesc Caballero-Lucas;Shota Kawabata;Godai Miyaji;Koji Sugioka

作者机构：RIKEN Center for Advanced Photonics2-1 HirosawaWako-shiSaitama 351-0198Japan Department of Applied PhysicsTokyo University of Agriculture and Technology2-24-16 NakachoKoganeiTokyo 184-8588Japan 

出 版 物：《International Journal of Extreme Manufacturing》 (极端制造（英文）)

年 卷 期：2023年第5卷第2期

页      面：208-214页

核心收录：

学科分类：08[工学] 0802[工学-机械工程] 080201[工学-机械制造及其自动化] 

基　　金：supported by MEXT Quantum Leap Flagship Program (MEXT Q-LEAP) Grant Number JPMXS0118067246 

主　　题：BiBurst mode GHz burst laser ablation silicon air ionization 

摘      要：For the practical use of femtosecond laser ablation, inputs of higher laser intensity are preferred to attain high-throughput material removal. However, the use of higher laser intensities for increasing ablation rates can have detrimental effects on ablation quality due to excess heat generation and air ionization. This paper employs ablation using BiBurst femtosecond laser pulses, which consist of multiple bursts(2 and 5 bursts) at a repetition rate of 64 MHz, each containing multiple intra-pulses(2–20 pulses) at an ultrafast repetition rate of 4.88 GHz, to overcome these conflicting conditions. Ablation of silicon substrates using the BiBurst mode with 5 burst pulses and 20 intra-pulses successfully prevents air breakdown at packet energies higher than the pulse energy inducing the air ionization by the conventional femtosecond laser pulse irradiation(single-pulse mode). As a result, ablation speed can be enhanced by a factor of23 without deteriorating the ablation quality compared to that by the single-pulse mode ablation under the conditions where the air ionization is avoided.